Many products have been created from the use of molding thermosetting plastics. This process typically requires the mixing of monomer resins with a polymerization initiator in a chemical process to create a polymer. This process has more recently been utilized as part of a process to create such products as dentures.
Dentures have been manufactured for centuries to replace all or part of an individuals dentition. More recently, dentures have been manufactured by molding the denture from casts made of the patient's existing dentition. The manufacturing process begins with a preliminary impression of the patient's mouth, which is usually done in wax. This impression is used to prepare a diagnostic cast. While making the impression, the dentist applies pressure to the soft tissues to simulate biting force and extends the borders of the mold to adjacent toothless areas to allow the dentures to better adapt to the gums. A final cast is then formed from the diagnostic cast from gypsum. The final mold is filled acrylic resin to form the denture. The appropriate resin compound are then mixed in liquid form and packed into the mold. A vertical vise may be used to pack the resin compound. Alternatively the liquid acrylic compounds may be poured into the mold. The mold is then heated to initiate the chemical reaction to harden or cure the compound. Once the compound has cured, the mold is broken apart and the denture is removed. The denture is then fitted to the patient with minor revisions.
This process is time consuming and costly. Further, a number of problems may occur during the molding process, particularly with acrylic. These include shrinkage and porosity issues.